Method of producing cathode sleeves for thermionic valve



Nov. 12, 1940. H; KERSHAW 2,220,910

METHOD OF PRODUCING CATHODE SLEEVES FOR THERMIONIC VALVES Originai FiledJan. 25 1940 2 Sheets-Sheet 1 H. KERSHAW .Ndv. 12, 1946.

METHOD OF PRODUCING CATHODE SLEEVES FOR THERMIONIC VALVES Original FiledJan. 23, 1940 2 Sheets-Sheet 2 -Patented Nov. 12, 1940 UNITED STATESLIETHOD OF PRODUCING CAT'HODE SLEEVES FOR THERMIONIO VALVES HenryKershaw, Belleviile, N. J.

Original application January 23, 1940, Serial No.

315,250. Divided and this application February 2'7, 1940, Serial No.321,125

13 Claims.

My invention relatesto a cathode sleeve for thermionic valves or vacuumtubes and to th method of producing the same.

In United States -Patent 2,029,482 a cathode 5 sleeve or cylinder isshown, formed from a strip of sheet metal, having its side edgesinterlocked, by providing oppositely facing bent tongues upon .thestrip. These interlocking edges provide a seam of four layers of metal,and the seam is conl tinued beyond one end of thetub'e or cylinder toprovide a tab, which is to be attached to a post. The tab is formed fromspaced tab sections at one end of'the sheet and each of these tab sec-'tions is folded upon itself to provide a continuation of theinterlocking tongues. Considerable difliculty is experienced, inproducing this sleeve or cylinder with the tab, as shown in Patent2,029,482, commercially, and the difficulty resides principally in theformation of the tab integral go with the sleeve or cylinder. As aresult of this, these sleeves or cylinders rdinarily are producedwithout the tabs which are separate from the sleeve or cylinder and aresubsequently welded to the sleeve or cylinder. This welding in place 25of the tab is a separate operation and increases the cost of productionof the product.

It has also been proposed to form the cathode sleeve or cylinder from anintegral drawn tube and to provide a separate tab, which is subse- 30quently welded to the drawn tube. This construction is shown in Patent2,079,057. The drawn tube is expensive.

In accordance with my method, I form a sleeve having generally radiallyextending flanges, and 5 portions of these flanges contact but theflanges do not interlock, and these flanges are welded together. Thesleeve may be accurately formed in the desired shape, such as circular,square, or other shape in cross-section, and the sleeve will not bedistorted by the welding of the flanges. The welding of the flangessecurely unite the side edges of the sleeve, and the welding may beeffected rapidly and cheaply. This dispenses with the expensive practiceof forming interlocking 45 tongues upon the side edges of the sleeve. Inthe practice of my method, the tab is formed of tab sections which arepreferably in effect continuations of the flanges. Each tab section issinglelayer and portions of their faces contact but have 50 nointerlocking engagement and are secured together by welding. Thedifiiculty experienced in shaping tab sections into interlocking tonguesis therefore eliminated, and the tab may be readily produced integralwith the sleeve or cylinder. I

55 may also bend over upon the sleeve or cylinder theoriginallygenerally radial welded flanges, providing a rib or seam. A portion ofthe welded flange may be left raised, for providing a shoulder. While itis preferred to bend down the welded flanges, the sleeve may be usedwithout 5 doing this. A further advantage of my construction is that therib or seam produced by the bentover welded flanges comprises but twolayers of metal, thus effecting the maximum uniform distribution ofheat. A further advantage of my construction is that the seam or rib maybe arranged wholly upon the exterior of the sleeve, thus permitting ofthe close arrangement between the electrical heating unit and thesleeve, without liability of these elements contacting and scraping-offthe insulationfrom the'.-heating....unit.

The present application is a continuation in part of my originalapplication for Cathode sleeve for thermionic valves and method ofproducing the same, Serial No. 259,908, filed March 4, 1939, and myapplication for Cathode sleeve for thermionic valves, Serial No.281,984, filed June 29, 1939, and which is a division of application259,908. The present application is also a divi- On of application315,250, filed Jan. 23, 1940 for Cathode sleeve for thermionic valves.

In the accompanying drawings forming a part of this application and inwhich like numerals are employed to designate like parts throughout thesame,

Figure 1 is a side'elevation, principally diagrammatic, illustratingapparatus used in the practice of the method for producing the cathodesleeve,

Figure 1 is a transverse section, parts broken away, taken. on line I* iof Figure 1,

Figure 2 is a perspective view of a portion of the ribbon or strip afterbeing bent in the V- shape, 1

Figure 3 is a side elevation of the forming roll- 40 ers which bend theflat strip into the V-shape and produce the row of raised portions atone longitudinal edge of the ribbon or strip,

Figure 4 is a perspective view of the V-shaped strip having the tabsections forming opening 5 stamped therein,

Figure 5 is a transverse section through the stamping punch, in thelowered position, as if taken on line 5- 5 of Figure 1,

Figure 6 is a perspective view of the strip trans- 60 versely cut toprovide the section or unit to form the cathode sleeve,

Figure 7 is a transverse section taken on line I-l f Figure 1, showingthe cutter,

Figure 8 is a central longitudinal vertical sec- 'tion through the lowerbed of the stamping and .holding device,

Figure 9 is a perspective view of the strip bent upon its longitudinalaxis to partly form the-cathode sleeve,

Figure 10 is a transverse section through the forming die and mandreland knock-down die, the partsbeing shown in the starting position,

Figure 11 is a similar view showing the forming die raised, the mandrelforced down, and the to provide strip bent about its longitudinal axisupstanding sides,

Figure 12 is an enlarged perspective view of the sleeve, with itsflanges and tabs welded together,

Figure 13 is an end elevation of the welding jaws, in the closedposition, illustrating the welding step for producing the sleeve shownin Figure 12, k

Figure 12" is an end elevation of the sleeve with the flanges slightlyspaced and the raised portions engaging oneflange,

Figure 13 is an end elevation of the sleeve, showing the flangescontacting and welded togetnzr and indicating the dimensions of the paFigure 1.4 is a bottom plan view of the welding Jaws,

Figure 15 is a perspective view of the sleeve, showing the weldedflanges bent down sleeve and slit to form a stop shoulder,

Figure 16 is a transverse section through the knock-down punch showingthe formation of the stop shoulder, the section through the knockdownpunch being taken on line 16-16 of Figure 1'7,

Figure 17 is a bottom down punch,

Figure 18 is a perspective view, in a vertical position of the completedcathode sleeve, and,

Figure 19 is a side elevation of the cathode sleeve shown in Figure 18,assembled with a grid and associated elements.

plan view of the knock- In Figures 15 and 18 I haveshown a cathodesleeve 20, which is cylindrlcal for the purpose of illustration. Thesleeve 20 has single-layer flanges 2| and 22, which overlain-are weldedtogether and bent over or down upon the sleeve, providing a seam of twolayers and which serves to stifien the sleeve. Tab sections 23 and 24are formed integral with the sleeve, are in alignment with the flanges2| and 22 and form in effect continuations of the same. The tab sectionsare also welded together. -Theflanges and tab sections have nointerlocking engagement and are secured together solely by welding. Theflanges 2i and 22 are arranged upon the outer surface of the sleeve andare transversely slit at 25, affording an outwardly projecting stopshoulder I 28, which is generally radial.

of the flanges and tab sections is .020" (20 thousandths of an inch).These dimensions may vary somewhat either way. Cathode sleeves are madehaving an internal diameter as small as .020" (20 thousandths of aninch). The dimenupon the recited to show the inherent diflicultiesencounner. As the metal ribbon is unwound from the spool it istransversely flat.

The step-by-step feed of the metal ribbon may be effected-by anysuitable means, and I contemplate using a block having a. flat recess3|.

Arranged above the block 30 is a top 32 rigidly secured thereto and thistop has a vertical opening 33, to receive a friction pin 34, forced downby a spring When the spring acts upon the friction pin 34 this frictionpin engages the ribbon 21 and holds it to the block 30 so that theribbon will move with the block when the block moves forwardly. Whenthe. block moves rearwardly, the intermediate portion of the spring 35is elevated, relieving the tension from the friction pin 34, and theblock may thenslide' rearwardly withrelation to the ribbon, which isthen held against rearward movement. The spring 35 is attached to the.top 32 and any suitable means may be employed to operate the spring andany suitable means may be employed to reciprocate the block 30. Theblock 30 is moved forwardly on each cycle of operation for a distanceequal to the combined length of the completed sleeve and tab sections.

The lower block 30 carries a forming roller 35, having a concaveperiphery whichfis channeled or V-shaped in cross-section and the roller36 coacts with an upper forming roller 31, carried by the top 32. Theroller 31 is convex and has a periphery which is V-shaped incross-section, corresponding to the cavity of the roller'36 and adaptedto enter the same. The low point 38 of the roller v36 is to one side ofthe center 99 of this roller, providing a face 40 longer than the face4|. The high point 42 of the roller 31 is to one side of the center 39providing a face 43 longer than the face 44. The upper roller 31 isprovided adjacent to one end of this periphery with an annular groove45, to receive an annular set of drawing studs 46, carried by the roller35.

When the block 30 and associated elements are moved from the rearposition, Figure 1, to the forward position, it will advance the ribbon21, as explained. When the ribbon is thus advanced, the forward portionof the ribbon is clamped against rearward movement and the tension ofthe spring 95 is released from the pin 34 and the block 30 andassociated elements are then moved rearwardly and returned to the rearposition. The block 30 and the forming rollers 3| and 31 then travelrearwardly with relation to the then stationary ribbon 21,'and theperipheriesof the forming rollers 39 and 31 engaging with the ribbon 21form or bend the same into a -V-shape, as shown. In this V-shape oneside 41 is wider than the other side 48. At the same time, the drawingstuds 46 produce a row of spaced raised portions 49 adjacent to onelongitudinal edge of the ribbon. These raised portions or bumps 49 havetheir convex faces next to the upper face of the side 41, Figure 2. The

ribbon is formed or bent into the V-shapeand the raised portions 49 areformed when the block 30 and associated elements move rearwardly withrespect to the ribbon. When the block 30 and associated elements moveforwardly, they feed the ribbon forwardly, and that portion which isV-shaped is rendered thereby stiff so that it is fed forwardly by apushing action, while that portion of the ribbon at the rear of theblock is fed forwardly by a pulling action. If the forward portion ofthe ribbon were not stiffened by the V-shape, it would not besufficiently stiff to be properly pushed forwardly.

When the V-shaped portion of the ribbon is pushed forwardly it is movedto a stamping position and is arranged within a V-shaped recess 50 of astationary die 5|, having a vertical opening 52, to receive a punch 53,carried by a vertically reciprocatory head 54. The numeral 55 designatesa stripper, having an opening 56 to receive the punch 53 and a groove 53to receive the raised portions 49 and move downwardly by springs 51. Thestripper 55 has its lower face v-shaped to conform to the shape of therecess 50. When the V-shaped portion of the ribbon 2'! is moved into therecess 50, the head 54 is shifted downwardly and the stripper 55 movesdownwardly and clamps the V-s'haped portion of the ribbon within therecess 50, subsequent to which the punch 53 moves down below thestripper 55 and enters the opening 52 of the die and stamps out theopening 51. When the head 54 rises, the punch 53 moves upwardly withrespect to the stripper 55 and the V-shaped portion of the ribbon willbe separated from the punchby the stripper. When the head 54 is in theuppermost position both the stripper and punch are spaced from theV-shaped portion of the ribbon. When the stripper 55 is clamping theV-shaped portion of the ribbon in the recess 50, the ribbon is heldagainst rearward movement, and during this time the block 30 andassociated elements are shifted rearwardly. The formation of the opening51 provides the tab sections 23 and 24, arranged adjacent to thelongitudinal edges of the V-shapecl portion of the ribbon and extendinglongitudinally of such V-shaped portion beyond one end of the same.

When the block 30 and associated elements are again moved forwardly thisV-shaped portion of the ribbon is advanced to the sleeve forming orbending position, and when the head 54 again moves downwardly, thecutter 50 is moved upwardly to sever the tab sections 23 and 24, at 59,whereby the leading V-shaped ribbon sec-tion is separated from theribbon. This section is used to form the sleeve and tab of the cathodesleeve. Particular attention is called to the fact that the raisedportions 49 extend throughout the entire length of the V-shaped portionand the entire length of the tab section 24. When the leading section isthus shifted to the bending position it is introduced into a V-shapedrecess 60 of a vertically movable forming die 6|, then in the loweredposition. The forming die also has a cylindrically curved recess 62,receiving the apex of the V-shaped section. The cylindrically curvedrecess 62 is preferably less than half of a cylinder whereby the sides41 and 4B of the section, when further bent extend upwardly in adiverging relation. The center of the recess 62 is to one side of thelongitudinal center 63 of the die 6|. The numeral 64 designates ahorizontal mandrel or core which is cylindrically curved for coactionwith the recess 62. The mandrel or core 64 is cylindrical except for anupper flat face 65, as

shown. The mandrel 64 is concentric with respect to the recess 62.During the forming of the sleeve, with the V-shaped strip within therecess 60, the mandrel 64 is held stationary above the die 6! and thedie is first raised sufi'iciently to clamp the V-shaped section betweenthe mandrel and the die and the die is then stopped before the mandrel64 has reached its lowermost position within the recess 62 and the die6| is held stationary. A knock-down die 66 is now moved downwardly intoengagement with the top of the mandrel 64 and forces it to the lowermostposition within the recess 62 and the mandrel 64 and the recess 62 nowbend the section to provide a lower cylindrically curved portion 61carrying the upstanding upwardly diverging sides 4! and 48. The side 41extends above the side 48, by virtue of the off-center arrangement ofthe recess 62 and the mandrel 64 and the Wider side 41 carries theraised portions 49. After this operation, the knock-down die 66 iselevated and separated from the mandrel 64. Horizontal reciprocatoryelectrical resistance welding jaws 68 and 69 are moved inwardly andengage the upstanding sides 41 and 48 and complete the forming orbending of the same about the mandrel 64 and form the flanges 2| and 22.These jaws 68 and 69 are insulated from parts 6| and 64. The welding jaw68 moves inwardly beyond the center 10 of the mandrel 64 while thewelding jaw 69 moves inwardly and terminates short of this center,whereby the flanges 2| and 22 are arranged adjacent to one longitudinaledge of the flat face 65 of the mandrel 64. The welding jaws 68 and 69have Vertically inclined welding faces H, which are preferably free fromnotches although notches may be used if desired. The welding jaws extendfor the entire combined length of the sleeve and the tab sections.

As the welding. jaws 68 and 69 move inwardly they first bring the convexends of the raised portions 49 of the flange 22 and tab section 24 intocontact with the flange 2| and tab section 23, and since these raisedportions are convex, the minimum area is afforded at the instant ofcontact between the raised portions and the flange and tab section,thereby producing the maximum resistance at the points of contact. Assoon as the jaws move inwardly sufliciently to effect the contact, asdescribed, a welding current is supplied to the welding jaws 63 and 69,and the raised portions 49 and the contacting portions of the flange andtab section are rendered plastic, and during this welding period thejaws 68 and 69 continue to move inwardly until the flanges and tabsections are brought into flrm contact and the raised portions or bumpsare flattened out. The inward pressure of the welding jaws 68 and 69follow through during the entire welding period so that there can be noflashing and the flanges and tab sections are brought into firm contactafter the raised portions are flattened, and the current is cut off whenthe jaws still exert the inward pressure. I use an alternating currentof low voltage and high amperage. Satisfactory results are obtained byusing an alternating current having a voltage of approximately three (3)Volts and an amperage of approximately 2,000 amperes. During the weldingperiod, the current stays on for only a short time, and I have foundthat satisfactory results are obtained by having the current turned onfor one-half /2) cycle. The invention is not restricted to the precisevoltage and amperage and time recited, as these may be varied. Thewelding jaws also weld the tab sections 23 and 24 together in the samemanner as the sides 2! and 22. The tab sections 23 and 24 are inalignment with the flanges 2| and 22 and are disposed in the planes ofthe same. The flanges and tab sections are arranged exteriorly of thesleeve, are inclined and are generally radial with relation to thesleeve and are disposed upon one side of the center of the sleeve. Themandrel or core 64 extends for the entire length of the sleeve and tabsection.

During the welding operation the die 6| and the mandrel B t remainstationary, and they remain stationary during the next step of bendingdown the welded flanges and tab sections. After the jaws 68 and 69 aremoved to the open position, the knock-down die 66 is again operated.This knock-down die 56 extends throughout the entire length of thesleeve and tab. The knockdown die has a cylindrically curved recess 12,having its center in alignment with the center of the recess 62. Theflanges 2i and 22 which are inclined are ofi-set with respect to thecenter of the sleeve and the center of the recess 12. It is thusapparent that when the knock-down die 66 again descends it will engagethe Welded flanges 2i and 22 and the tab sections 23 and 24 and bendthem down over the flattened portion of the sleeve, and this bendingdown will occur throughout the entire length of the sleeve and the tabexcept for a short portion which provides the upstanding stop shoulder26. The shoulder 26 is provided by forming the knock-down die 66, Figure16, with a transverse slot 73 having a width corresponding to the lengthof the shoulder 26. A supporting element or hook 'M extends into theslot 73 and is adapted to engage behind the shoulder 26, to prevent thesame being bent down. The hook i supports the shoulder 26 and the edgesof the slot 13 serve to out or shear the 0 flanges 2! and 22 at thelines 25. The hook elesuitable means.

ment never moves downwardly sufliciently to engage the mandrel or sleevethereon but does move downwardly sufflciently to engage behind theshoulder 26. The hook may be operated by any I have shown a spring 75 toraise the hook and an adjustable screw 16 carried by the knock-down die60 to depress the hook. When the die 86 is raised the space between thescrew !5 and the hook M is such that the face of the recess 12 of thedie 66 will engage the sleeve upon the mandrel 64 before the hook it hasmoved downwardly to engage such sleeve.

After the bending down operation the knockdown die is raised, the hookl4 rises and the 55 forming die 61 is lowered and the mandrel 66 ismoved horizontally through a strip-per ll which strips the completedsleeve from the mandrel. This completes the cycle of operation of themethod. The various instrumentalities employed in the practice of themethod will be moved in properly timed order, and they may be movedmanually or automatically.

The sleeve shown in Figure 18 is thereby produced, and the bent-downflanges 2i and 22 provide a seam of two layers, forming three layerswith the adjacent part of the sleeve, and the shoulder 26 is at or inthis bent-down seam. In Figure 19 I have shown the cathode sleeve 20 ofFigure 18 assembled with a grid 18 and anode 1c, in a manner somewhatsimilar to the arrangement shown in Figure 4 of Patent 2,079,057. InFigure 19 the numeral designates an upper mica disk and 8! designates alower mica disk, supported by posts 82. The sleeve 20 contains the usualresistance element or heater including lead-in wires 83 and the sleeveis coated at 84 with barium or strontium carbonate, corresponding to thecoating I! of Patent 2,079,057. This coating when raised to the propertemperature becomes a good emitter of electrons. The tab 22 formed bythe tab sections 23 and 24 may be bent slightly so that it can beattached or welded to one of the posts 49. The shoulder 23 rests uponthe top of the disk 8!, and supports the sleeve, the ends of which areinserted within openings 85.

It is to be understood that the form of my invention herewith shown anddescribed is to be taken as a. preferred example of the same and thatvarious changes in the shape, size, and arrangement of parts may beresorted to without departing from the spirit of my invention or thescope of the subjoined claims.

Having thus described my invention, what I claim is:

l. The method of producing a cathode sleeve for a thermionic valve,comprising stamping an opening in one end of a metal strip to providelongitudinally extending tab sections formed integral with the stripnear its longitudinal edges, bending the strip carrying the tab sectionsabout its longitudinal axis, applying pressure to the outer sides of thestrip near its longitudinal edges to complete the bending for forming asleeve having laterally and outwardly extending flanges with the tabsections constituting continuations of the flanges, each flange and eachtab section consisting of a single layer, and welding the flangestogether and the tab sections together while maintaining each flange andeach tab section in the single-layer condition.

2. The method of producing a cathode sleeve for a thermionic valve,comprising forming longitudinally extending single-layer tab sectionsintegral with and upon one end of a strip of sheet metal adjacent to thelongitudinal edges of the strip, bending the strip about itslongitudinal axis to produce the sleeve and forming longitudinalsingle-layer flanges at the side edges of the sleeve, the tab sectionsconstituting extensions of the flanges, and welding the flanges togetherand the tab sections together while maintaining each flange and each tabsection in the single-layer condition.

3. The method of producing a cathode sleeve for a thermionic valve,comprising forming an opening in a metallic sheet for providing a bodyportion and spaced single-layer tab sections extending longitudinallybeyond one end of the body portion, bending the body portion about itslongitudinal axis for forming a sleeve and singlelayer longitudinalflanges projecting laterally of the sleeve, and welding the flangestogether and the tab sections together while maintaining each flange andeach tab section in the single-layer condition.

4. The method of producing a cathode sleeve for a thermionic valve,comprising forming an opening in a. metallic sheet to provide a bodyportion and spaced single-layer tab sections adjacent to thelongitudinal edges of the body portion and extending beyond the end ofthe body portion, bending the body portion about its longitudinal axisfor forming a sleeve and single-layer longitudinal flanges projectinglaterally beyond the outer surface of the sleeve while causing the tabsections to substantially align with the flanges, bringing the flangesin opposed substantially parallel close relation while bringing the tabsections in opposed substantially parallel close relation, and weldingthe flanges together and the portion having longitudinal edges andlongitudinally extending spaced single-layer tab .sections adjacent tothe longitudinal edges, bending the body portion about its longitudinalaxis for forming a sleeve and single-layer longitudinal flangesprojecting laterally uponthe outer side of the sleeve, bringing theflanges in opposed close relation and bringing the tab sections inopposed close relation, and welding the flanges together and welding thetab sections together while maintaining each flange and each tab sectionin the single-layer condition. y

6. The method of producing a cathode sleeve for a thermionic valve,comprising forming an opening in a metallic sheet to provide a bodyportion andspaced single-layer tab sections extending beyond the end ofthe body portion, bending the body portion about its longitudinal axisfor forming a sleeveand single-layer longitudinal flanges projectinglaterally upon the outer surface of the sleeve, arranging the flanges inoverlapping relation and welding them together and arranging the tabsections in overlapping relation and welding them together whilemaintain- ,mg each flange and each tab section in the singlelayercondition, and bending down a portion of the welded together flanges tolie in close relation upon the outer surface of the sleeve.

7. The method of producing a cathode sleeve for a thermionic valve,comprising forming an opening in a metallic sheet to provide a bodyportion and spaced single-layer tab sections extending beyond one end ofthe body portion, bending the body portion about its longitudinal axisfor forming a sleeve and single-layer longitudinal flanges projectinglaterally upon the outer surface of the sleeve, arranging the flanges inoverlapping relation and the tab sectionsin overlapping relation,welding the flanges together and the tab sections together, bending downa portion of the welded flanges upon the outer surface of the sleeve,and forming a stop shoulder upon the flanges.

8. The method of producing a cathode sleeve for a thermionic valve,comprising stamping an opening in one end of a metal strip to providelongitudinally extending tab sections formed integral with the stripnear its longitudinal edges,

.forming raised portions along one longitudinal edge and one tabsection, bending the strip carrying the tab sections about itslongitudinal axis andapplying pressure in an inward direction to thestrip adjacent,to its longitudinal edges and the tab sections, forforming a sleeve having outwardly extending flanges, each flange andeach tab section consisting of a. single layer, and welding the flangestogether-and the tab sections to-.

gether while maintaining each flange and each tab section in thesingle-layer condition.

9. The method of producing a cathode sleeve for a thermionic valve,comprising forming longitudinaily extending tab sections integral withand upon one end 0! a. sheet metal strip adjacent to the longitudinaledges of the strip, forming a group of raised portions upon the stripwhichgroup extends longitudinally of one longitudinal edge and one tabsection, bending the strip about its longitudinal axis to produce thesleeve and forming longitudinal single-layer flanges, and

welding the flanges together and the tab sections together whilemaintaining each flange and each tab section in the single-layercondition. a 10. The method of producing a cathode sleeve for athermionic valve, comprising forming a group of raised portions adjacentto and extending longitudinally of one longitudinal edge of an elongatedstrip, stamping an opening in one end of the strip to providesingle-layer tab sections with the raised portions upon one tab section,bending the strip about its longitudinal axis into a sleeve havingsingle-layer flanges at the longitudinal edges, and bringing the flangesand tab sections into close relation and welding the same together whilemaintaining the tab sections and the flanges in the single-layercondition and securing them together solely by the welding.

11. The method of producing a cathode sleeve for a thermionic valve,comprising bending a flat elongated metallic strip into a. V-shape andforming a group of raised portions adjacent to one longitudinal edge ofthe strip and extending longitudinally of the edge, formlngan opening inone end of the strip to provide longitudinal singlelayer tab sectionswith the raised portions extending longitudinally upon one tab section,bendingthe V-shaped strip about its longitudinal axis to form a sleeveto provide overlapping singlelayer portions and for causing the tabsections to overlap, and welding the overlapping portions and theoverlapping tab sections together while maintaining the tab sections andthe overlapping portions in the single-layer position and securing themtogether solely by the welding.

12. The method of producing a cathode sleeve for a thermionic valve,comprising forming an opening in a metal strip to provide longitudinallyextending single-layer tab sections formed integral with the strip nearits longitudinal edges, bending the strip about its lo'ngitudinalaxisfor forming asleeve and generally radial outwardly extendingsingle-layer flanges and inclining the flanges, welding the flangestogether and the tab sections together while maintaining the flanges andtab sections in the single-layer condition and thereby securing the sametogether solely by the welding, and applying pressure to the inclinedflanges in a direction toward the sleeve to benddown the inclinedflanges.

13. The method of producing a cathode sleeve for a thermionic valve,comprisingiorming single layer tab sections integral with a. metal stripadjacent to the longitudinal edges of the metal strip, bending the stripabout its longitudinal axis to produce the sleeve and forminglongitudinal single-layer flanges at the side edges of the sleeve, thetab sections extending beyond the sleeve from points adjacent to theflanges, and welding the flanges together and the tab sections togetherwhile maintaining each flange and eachtab section in the single-layercondition.

HENRY masrmw.

